1. Field of the Invention
This invention pertains to a zoom lens system, and more particularly, to a high-power zoom lens system suitable as a photo-taking lens used in a camera.
2. Description of the Related Art
Conventionally proposed four-component zoom lens systems having a positive lens unit, a negative lens unit, a positive lens unit and a negative lens unit in that order have approximately a .times.3 zoom ratio.
However, with said conventional model, if the zoom ratio is further increased, an adequate back focal distance cannot be preserved. In addition, if the zoom ratio is made .times.3 or larger, transverse chromatic aberrations increase when the zoom lens system is in the telephoto condition.